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21 August 1977

The world’s longest space exploration began today with the launch of a Voyager spacecraft from Kennedy Space Center at Cape Canaveral, Florida. In 1990 it could still be sending back information from the outer reaches of the solar system, four thousand million miles away.

Its main purpose is to provide close-up pictures and scientific data about two of the outer planets, Jupiter and Saturn, both huge and somewhat insubstantial bodies consisting largely of the gases hydrogen and helium.

The Voyager spacecraft – another is to follow within the next fortnight – will take a close look at Saturn’s rings and at the moons of both planets.

The most interesting of these seems likely to be Titan, a Saturnine satellite almost half as big as the earth. Titan appears to have an atmosphere consisting of a mixture of methane and hydrogen and might even have oceans full of liquid methane.

The two spacecraft will also pass close to Jupiter’s satellites Callisto, Ganymede, Io, Europa and Amalthea (the first four were discovered by Galileo and take their names from Jupiter’s lovers) before using Jupiter’s huge gravitational field to swing them round on target for Saturn.

Assuming the spacecraft are still in good shape after looking at Saturn, its rings and its satellites, one of them will continue to Uranus, recently discovered to have Saturn-like rings.

Uranus will be reached in 1986, and then the spacecraft might be able to fly on to Neptune, the outermost of the planets. Only once in every one hundred eighty years do the planets line up conveniently enough to make such a grand tour possible.

After Neptune, the spacecraft will glide off into the abyss of interstellar space, carrying with them some earthly artefacts in case they ever fall into the hands of civilizations way out in space. The cargo includes a recorded message from President Carter, some music (Bach and Chuck Berry), a complete listing of the membership of the US Congress and information in sixty languages.

The chances that this message in a bottle will ever land on a friendly shore are infinitesimally small, and one or two scientists have grumpily accused the National Aeronautics and Space Agency of gimmickry.

But it does no harm, takes up little of the spacecraft’s cargo capacity, may have helped to extract the money from Congress and makes the stern scientific purposes of the mission seem more human.

[Both Voyager spacecrafts are still in operation, nearing interstellar space.]

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